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Lawyers Look to Exploit a Scientific Error

The spying indictment filed late last week against a former Los Alamos scientist contains evidence of tape-recorded conversations, clandestine meetings, confidential places for the transfer of documents and a pattern of false statements.

But the indictment also contains a glaring scientific error, which is prompting debate among legal and nuclear experts on whether the government’s case could be hurt.

“At a minimum, it’s incredibly sloppy but it tends to undermine the credibility of the entire indictment,” said Steven Aftergood, a security expert at the Federation of American Scientists. “Anyone who has read a book about nuclear weapons,” he added, would have spotted the mistake.

Federal prosecutors charged the scientist, P. Leonardo Mascheroni, and his wife, Marjorie, with trying to sell classified nuclear information to a foreign power. The two were arraigned Monday in Albuquerque and pleaded innocent. If convicted, both face up to life in prison.

According to the indictment, Dr. Mascheroni told an F.B.I. agent posing as a Venezuelan spy that a secret nuclear reactor could be constructed underground for “enriching plutonium,” the fuel of most nuclear arms.

But specialists agree that reactors cannot enrich plutonium. The government’s reference to enrichment, they say, refers to a separate process in which hundreds or thousands of spinning machines purify uranium, another bomb fuel.

“It doesn’t make sense,” Harold M. Agnew, a former director of Los Alamos, said of the enrichment claim in an interview. “I haven’t the slightest idea what that would be about.”

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Charles P. Demos, a former official with the Department of Energy, which runs the nation’s nuclear weapons program, agreed. “You don’t enrich plutonium,” he said in an interview. “You create plutonium.”

The mistake could prove inconsequential legally, since the Department of Justice could file what is known as a superseding indictment, which adds or corrects information in the original charges. The erroneous phrase would then be removed.

But already, defense lawyers are citing the phrase in an effort to undermine the prosecution, and they could also cite any corrections in the indictment as part of their defense.

“This raises questions about the credibility of the allegations,” said Erlinda Ocampo Johnson, a lawyer for Mrs. Mascheroni. “We’re going to dissect every bit of the case to make sure the government has not overstepped its bounds.”

The technical error is particularly embarrassing, some lawyers said, because of the bungled case that federal prosecutors brought against Wen Ho Lee, another former scientist at the Los Alamos National Laboratory, in 1999. In that case. Dr. Lee was charged with mishandling nuclear weapon secrets with the intention of aiding a foreign power. But the criminal case unraveled after defense lawyers zeroed in on factual errors, procedural missteps and conspicuous gaps in the evidence.

A Department of Justice spokesman, Dean Boyd, said its officials would make no comment about the phrase in question. “We look forward to presenting our case in court,” he said, “and will let a jury decide the guilt or innocence of the defendants.”

A version of this article appears in print on September 24, 2010, on Page A16 of the New York edition with the headline: Lawyers Look to Exploit a Scientific Error. Order Reprints|Today's Paper|Subscribe